Excitations of the unstable nuclei ^{48}Ni and ^{49}Ni

Abstract

The isoscalar E1 and E2 resonances in the proton-rich nuclei ^{48,49}Ni and the {f_{7/2}3^-} multiplet in ^{49}Ni have been calculated taking into account the single-particle continuum exactly. The analogous calculations for the mirror nuclei ^{48}Ca and ^{49}Sc are presented. The models used are the continuum RPA for ^{48}Ni, ^{48}Ca and the Odd RPA for ^{49}Ni, ^{49}Sc, the latter has been developed recently and describes both single-particle and collective excitations of an odd nucleus on a common basis. In all four nuclei we obtained a distinct splitting of the isoscalar E1 resonance into 1 h-bar omega and 3 h-bar omega peaks at about 11 MeV and 30 MeV, respectively. The main part of the isoscalar E1 EWSR is exhausted by the 3 h-bar omega resonances. The 1 h-bar omega resonances exhaust about 35% of this EWSR in ^{48,49}Ni and about 22% in ^{48}Ca and ^{49}Sc. All seven {f_{7/2}3^-} multiplet members in ^{49}Ni are calculated to be in the (6-8) MeV energy region and have noticeable escape widths.